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<p>Eutectic medium-entropy alloys (EMEAs) present a pathway to overcome the strength–ductility trade-off, yet their nanoscale scaling laws remain unexplored. Using large-scale molecular dynamics simulations, we investigate size-dependent deformation in dual-phase AlCrFeNi EMEAs across varying interlamellar spacings. Results reveal a non-monotonic yield strength scaling, where traditional Hall–Petch strengthening transitions to inverse Hall–Petch softening at a critical spacing of approximately 192 nm. Notably, this breakdown occurs at a length scale over an order of magnitude larger than the <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\sim\)</EquationSource> <EquationSource Format="MATHML"><math> <mo>∼</mo> </math></EquationSource> </InlineEquation>10 nm threshold typical of single-phase nanocrystalline metals. Atomistic analysis demonstrates that this mechanical transition originates from a fundamental shift in the dominant plasticity mechanism, where interphase boundaries evolve from rigid barriers that facilitate dislocation pile-up to active, compliant sites that mediate boundary-controlled deformation. These findings provide a theoretical framework for the structural optimization of nanostructured MEAs, highlighting a new regime for designing ultra-strong, damage-tolerant heterogeneous materials.</p>

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Early breakdown of Hall–Petch strengthening in eutectic medium-entropy alloys

  • 期刊论文

  • 发表日期：

    2026年7月30日

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  • Van-Lam Nguyen,
  • Minh-Quan Doan,
  • Le Van Lich

摘要

Eutectic medium-entropy alloys (EMEAs) present a pathway to overcome the strength–ductility trade-off, yet their nanoscale scaling laws remain unexplored. Using large-scale molecular dynamics simulations, we investigate size-dependent deformation in dual-phase AlCrFeNi EMEAs across varying interlamellar spacings. Results reveal a non-monotonic yield strength scaling, where traditional Hall–Petch strengthening transitions to inverse Hall–Petch softening at a critical spacing of approximately 192 nm. Notably, this breakdown occurs at a length scale over an order of magnitude larger than the \(\sim\) ∼ 10 nm threshold typical of single-phase nanocrystalline metals. Atomistic analysis demonstrates that this mechanical transition originates from a fundamental shift in the dominant plasticity mechanism, where interphase boundaries evolve from rigid barriers that facilitate dislocation pile-up to active, compliant sites that mediate boundary-controlled deformation. These findings provide a theoretical framework for the structural optimization of nanostructured MEAs, highlighting a new regime for designing ultra-strong, damage-tolerant heterogeneous materials.